County outlines special‑exception process as Bonner residents press concerns over proposed data center

Missoula County planning staff briefed the Bonner Milltown Community Council on April 13 about a proposed AI/data center at the Bonner Mill site and the special‑exception process that will determine whether the project can move forward given nearby residences.

Karen Hughes, the county’s director of planning, development and sustainability, said the project “will go through what’s called a special exception process” because data centers located within 500 feet of residential zoning are required to have that review. She told attendees the consolidated land use board will consider a narrow set of criteria focused on how the facility would interface with adjacent residences, including access, parking, traffic, lighting, noise and screening.

The county will notify property owners within the 500‑foot radius by mail, publish legal notices and maintain a project page on MissoulaCountyVoice, Hughes said. “We notify people by mail … we put a legal ad in the paper … and then we also have a post … on MissoulaCountyVoice,” she said, adding that staff will summarize public comment for the board.

Jenny Dixon, the county case planner assigned to the application, said the special‑exception review is deliberately narrow. “It’s not really reviewing the use … but rather how the data center interfaces with the residential,” Dixon said. She noted that the county’s 2022 code updates added noise, lighting and landscaping standards intended to reduce impacts from operations such as large crypto mines and data centers.

Residents focused much of their questioning on three recurring topics: water use and water rights, noise and vibration from fixed equipment, and whether the county can hold the applicant to proprietary technical claims.

On water, Karen Hughes said water‑quality and quantity oversight involves multiple agencies. “The health department is really … the Missoula Valley Water Quality District will be looking at that at the time of zoning compliance,” she said, and DNRC would be involved if water rights or quantity became an issue. Attendees pressed the county to bring DEQ and public‑health representatives to a future meeting to answer technical questions.

Mike Eisen, the Bonner site water operator, provided metered historical usage for buildings on the site and said some commonly cited data‑center water figures appeared less alarming in context. “I pump about 800 gallons a day into that building … so 500 gallon per megawatt … is not a lot of water to me,” he said, describing long‑term logs that inform his view.

On noise, county staff described the 2022 standards that establish maximum levels and said enforcement is complaint‑driven. Dixon noted the county now addresses both decibel and frequency concerns: “If a fixed source of noise … generates above the threshold, we would receive complaints … and we’ll pursue enforcement.”

Several speakers asked how the county would verify proprietary systems that the applicant has described in public presentations. Hughes said the county’s review authority is limited to zoning criteria but that staff will solicit technical comment from relevant agencies and consult legal counsel about whether conditions can be written to hold the applicant to proposed systems.

On energy, staff reiterated that applicants must demonstrate that new renewable energy will supply the project. “We expect to require … that they are providing new renewable energy for their entire operation,” Hughes said; planners will verify that requirement during zoning‑compliance permitting after — and only if — the special exception is approved.

Multiple residents raised broader concerns about company transparency and long‑term effects, urging the county to require more specific technical data earlier in the review. County staff said the consolidated land use board hearing is currently scheduled for June 3 and reminded residents that public comment on MissoulaCountyVoice and at the hearing becomes part of the written record the board will review.

What happens next: county planners will post application materials and mailing notices, solicit comments from agencies (health, DEQ, DNRC), and prepare a staff report for the consolidated land use board. The board typically hears testimony at the hearing and issues a decision; if the board finds any single required criterion not met, it must deny the special exception.

The consolidated land use board hearing is currently scheduled for June 3 (time and location posted on the county engagement page).